<div
  class="ui-grid-tree-base-row-header-buttons"
  ng-class="{'ui-grid-tree-base-header': row.treeLevel > -1 }"
  tabindex="0"
  ng-keydown="treeButtonKeyDown(row, $event)"
  ng-click="treeButtonClick(row, $event)">
  <i
    ng-class="treeButtonClass(row)"
    ng-style="{'padding-left': grid.options.treeIndent * row.treeLevel + 'px'}">
  </i>
  &nbsp;
</div>
